This invention relates to an apparatus for cutting cloth and other similar sheet material spread over a knife penetrable bed defining a support surface, and deals more particularly with an improvement in such an apparatus wherein means are provided for adjusting the lower limit of travel of the reciprocating knife of a cutter head in response to shortening of the knife at its tip occurring as a result of its being sharpened, so that during cutting operations the knife is maintained at an optimum bed penetration depth throughout its service life.
In known machines for cutting sheet material spread on a supporting surface, the lower end of a knife plunges into a bed providing the supporting surface while it is reciprocated and moved forwardly during a cutting operation to cut sheet material on the surface. One such machine is disclosed in U.S. Pat. No. 4,841,822 issued on June 27, 1989. In the machine of this patent, a cutter head including a knife moves between raised and lowered positions relative to a support carriage and relative to the material supporting surface. When the cutter head is in its raised position, the knife is held entirely above the material in a non-cutting condition, and when the cutter head is moved from its raised to its lowered position the lower end of the knife is plunged through the material and into the bed where it remains during a cutting operation.
In such previously known machines, the lowered position of the cutter head has been fixed relative to the support carriage and to the material supporting surface. This has the disadvantage that as the knife becomes shortened due to repeated sharpenings the lower end of the knife may eventually not penetrate the material supporting bed to the extent desired for proper cutting.
Accordingly, it is an object of the present invention to provide in a cloth cutting machine or the like an adjustable limit stop for the knife providing cutter head to vary the lowermost limit of travel of the cutter head so that the lower end of the knife may be maintained properly within the associated knife penetrable material supporting bed regardless of shortening of the knife by repeated sharpening.
It is yet another object of the present invention to provide a variable limit stop of the foregoing character operating with a controller to adjust the lowermost limit of travel of the cutter head relative to the bed in accordance with the number of sharpening operations executed on the knife.
Other objects and advantages of the invention will be apparent from the following description and drawings and from the appended claims.